Two-speed polyphase dynamoelectric machine



Nov. 20, 1951 L. A. KILGORE 2,575,716 TWO-SPEED POLYPHASE DYNAMOELECTRICMACHINE Filed Sept. 2, 1950 24 F lg. l.

2 4-Pole o 29 8 2T 26" 1 IZ-Pole s4 INVENTOR Lee' A. KHgore.

BY 9 2 Z Z ATTORNEY Patented Nov. 20, 1951 -UNITED PST-ATES PATENTOFFICE TWO-SPEED POLYPHASE DYNAMO- ELECTRIC MACHINE Lee A. Kilgore,Export, Pa., assignor to Westinghouse 'Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Application September 2,1950, Serial No. 183,001

' 4Claims. (Cl. 318-224) My invention relates to improvements in theswitching-arrangements for polyphase, 2-speed, 2-to-1 pole number,induction-motors, synchronous motors, or other polyphasedynamo-electricmachines, having four poles, or a multiple of four poles, iorits highpole-number.

The principal object of my invention is toreduce the number ofswitching-poles which are necessary to change from one pole-number tothe othenwhile retaining the advantages of 60- degree phase-belts 'orwinding-groups, in a 3- phase motor.

iMy invention" is an improvement over the] consequent-pole "change-speedinduction-motors in which the winding was changed from a seriesarrangementto a two-parallel arrangement'in which the direction of thecurrent-flow was reversed in'every other group of the winding for thelow-speed connection, as described, for example, in an article by C.- W.Kincaid in'the Electric Journal for August'l924, page'357. This oldconsequent-pole connection, while requiring few switching-polesyhad manyserious disadvantages, including even harmonics, which cause extralossesand noise, and a higher leakagere actance' and a lowerdistribution-factor than a 60 phase-belt S-phase winding.

My present invention is also an improvement over previously known 60phase-belt 3-phase windings, such'as were described in the Lewis Patent1,495,420, granted May 27,1924, in which a "very large number ofcontactor-poles were used, in a complicated Wiring-arrangementpasdistinguished from the simple change-over connections which arenecessary, if a commercially practicable two-speed motor is to beproduced. "In general, my new motor or'dynamo-electric machine ischaracterized by usingpermanently closed rings, each consisting or" fourphase-belts or winding-groups,-and by making connections to these ringsso as to provide a-two-parallel winding for the four-pole connection,and a fourparallel winding for the two-pole connection.

#While my invention is susceptible "of'embodiment in a number ofdifferent forms, I have illustrated two of the simplest forms ofembodiment in. the accompanyingdrawings, in a 4/2- pole motor, which isintended to be'representative of. any multiples of these pole-members,which are obviously obtainable by mere duplica tion or repetition of thewinding-poles which are illustrated. While my invention isnot' limitedto 3-phase motorsorto motors as distinguished from generators, by farthe most important held of application of=-my invention isin S-phasemotors, and so I have illustrated my invention as 'a B-phase motor, withthe understanding that this illustration is not to be taken in alimiting sense.

In the accompanying drawing, Fig. l is a diagrammatic view of circuitsand apparatus of a 4/2-po1e 3-phase squirrel-cage.induction motor, withall switching and control-connections necessary for producing either atwo-pole fourparallel Y or stareconnection, a four-pole twoparallel Y'orstar connection, or a four-pole twoparallel delta-connection,

Fig. 2 is a diagrammatic view of'the four-pole two-parallelstar-connection,

Fig. 3 is a similar view of the two-pole four- .parallelstar-connection,

Fig. 4 is a'similar viewof'the four-ipole twoparallel delta-connection,and

Figs; 5 and 6 are developed diagrammatic views illustrative of theenergization of the twelve phase-beltsor winding-groups, necessary toproduce a 3-phase four-pole machine, and a 3-phase two-pole machine,respectively.

In 'Fig. l', Ihave illustrated the application of my invention in a3-phase squirrel-cage induction-motor, although it is also applicable tosynchronous motors and generators. In the illustrated machine, theprimary winding consists of twelve identical phase-belts orwinding-groups, following each'other consecutively around thecircumference of the primary winding, and numbered consecutively from Ito l2,with polaritymarks and to indicate the beginning and end,respectively, of each winding-group. A developed view of the primarywinding is again indicated in each of Figs. 5 and 6, to which have beenaddedarrows showing the direction of the current-flow of the 3-phasecurrents A, B and C, which are necessary to make four poles and twopoles, respectively.

It will be understood, of course, that the numbering of the consecutivewinding-groups I to 12 can be started at any winding-group, and that thelettering of the phases A, B and C can be started by calling'any phaseA, and the other two phases B and C, in either phase-sequence. It isalso to be understood that the phases A, B and C, which are indicated inFigs. 5 and 6, can be either star-phases or delta-phases, the letters A,B and 0 here indicating only that the chosen principal phase is markedA, the next lagging (or leading) phase is marked B, and the third phaseis marked C.

It will be noted, from a comparison of Figs. 5

and (i, that one of the winding-groups has the phase-A current flowingin it, in the same direction, in both the four-pole arrangement and thetwo-pole arrangement, and I have arbitrarily chosen the convention ofassigning the number I to this particular winding-group. In thefollowing description and claims, this numberingconvention will be used,with the understanding, however, that any other system of numbering orlettering might have been chosen.

An examination of Fig. 5 will show that, for the four-pole arrangement,the phase-A current will flow in the same direction in the windinggroupsI and I, and will flow in the reverse direction in the winding-groups 4and I0. This will make the winding-groups l and I produce north poles ata given instant, while the winding-groups 4 and I produce south poles atthe same instant. Similar observations can be made for the other twophase-currents B and C, with appropriate changes in the numbering of thewinding-groups. It will be noted that each winding-group, in thefour-pole arrangement of Fig. 5, will have a beltwidth of 60, or /12 offour poles of 180 each.

Reference to Fig. 6 will show that the first two winding-groups I and 2have the phase-A current flowing therein in the same direction, whilethe seventh and'eighth winding-groups have the phase-A current flowingtherein in the reverse direction, thus making groups I and 2 togetherproduce a north pole at the same instant when the groups I and 8together produce a south pole. Here, again, a 60" phase-belt is producedby the two winding-groups I and 2 together, and by the twowinding-groups I and 8 together.

If the phase which I have marked B had been chosen as the principalphase, and marked A, in both Figs. 5 and 6, then phase-winding I2 wouldhave been marked I, but the ending-terminal* of the phase-winding wouldbecome an entrance-terminal, and the order of sequence of the numberingswould therefore be reversed, thus making group II have the number 2,group I0, 3, and so on. In this way, the first two groups of the newnumbering would carry the phase-A current in Fig. 6.

A comparison of Figs. 5 and 6 will show that, in changing from thefour-pole arrangement of Fig. 5 to the two-pole arrangement of Fig. 6,the

phase-A current flows in both of the windinggroups I and I in bothfigures, but with the direction of current-flow reversed in Fig. 6, ascompared to Fig. 5. Thus, I can connect the winding-groups I and I inseries with each other, in Fig. 5, bringing the phase-A current into thebeginning of group I, thence to the beginning of group I, and finallyout of the end of group I, for the four-pole connection of Fig. 5. Then,for the two-pole connection of Fig. 6, I can bring the phase-A currentinto the junction-point between the end of group I and the beginning ofgroup I. In this way, I will have effected a reversal of thecurrent-direction in the winding-group I, without changing thecurrentdirection in the windinggroup'l.

A further comparison of Figs. 5 and 6 will show that, while the phase-Acurrent flows in the winding-groups 4 and II] in the four-polearrangementof Fig. 5, the same winding-groups 4 and II) are traversed bythe phase-C current in the two-pole arrangement of Fig. 6, but with thepolarity or direction of current-flow reversed in the winding-group I0.Consequently, for the four-pole connection of Fig. 5, I connect thewinding-groups I0 and 4 in series, with the phase-A current entering atthe end of group I0, and

thence passing on to the end of group 4, and leaving at the beginning ofgroup 4. For the twopole arrangement of Fig. 6, I bring the phase-Ccurrent into the junction-point between the groups I0 and 4, so that thephase-C current enters group II] at its beginning, and enters group 4 atits ending, thus effecting the necessary current-reversal orpolarity-reversal of the coil I0.

These four phase-A coils, I, I, I0 and 4, of the four-pole connection ofFig. 5, are thus permanently connected together in a closed loop, as isshown in Figs. 1, 2 and 4. For the four-pole connection of Fig. 4, thephase-A current is brought in at the junction-point a, between groups Iand I0, and the phase-A current is brought out at the junction-point 11*between groups 4 and. I. For the two-pole connection, the phase-Acurrent is brought in at the junction-point between the beginning ofgroup I and the ending of group I, while the phase-C current is broughtin at the junction-point between the ending of group 4 and the beginningof group I6. Adding eight to the number of each of the four windinggroups I, I, I0 and 4 of phase-A, will produce the phase-B loop,consisting of winding-groups 9, 3, 6 and I2 (subtracting 12 whenever thenumber exceeds 12). Adding eight more, produces the phase-C closed ringor loop, consisting of the windinggroups 5, I I, 2 and 8. Appropriatechanges will be made, of course, in the lettering of the phasecurrentsand terminals, for the respective fourwinding Icons. I

Expressed more generically, whatever the number of phases, and whateverthe multiple of four poles for the high pole-number of the winding,there is one phase-belt or winding-group per phase per pole of theslow-speed (high-pole-number) connection. There are permanentconnections forming a separate closed ring of four winding-groups perphase per four poles of the primary winding; each ring forms twoparallel circuits for each group of four poles of the highpole-numberconnection; one of these two parallel circuits consists of two seriallyconnected winding-groups, such as I and I, which are similarly situatedin two different north poles at any given instant; and the otherparallel circuit of each ring consists of two winding-groups, such as Inand 4, which are serially connected in the opposite polarity, and whichare similarly situated in two different south poles at the aforesaidinstant. For the slow-speed, or high-po1e-number, connection, each ofthe aforesaid pairs of parallel circuits is energized from its ownproper phase. For the high-speed, or low-pole-number, connection, thetwo intermediate junction-points, between the winding-groups which werein series with each other in the high-speed connection, are energizedfrom the polyphase supply, to make a four-parallel connection for eachphase, for the low-pole-number connection of the primary windmg.

If the motor has 8 poles, or 12 poles, or any other multiple of 4 poles,for its high-pole-number connection, then it is not necessary that thetwelve phase-belts or winding-groups which are consecutively numbered Ito I2 shall all be within four consecutive poles of the high-pole-numberconnection. The consecutively numbered groups I to I2 should have thesame phase-relations as if said groups followed each other consecutivelyunder the first four poles of the motor, but group 4, for example, couldbe underthe sixth pole instead of the second pole, and group III, forexample, could be under the eighth or twelfth pole instead of the fourthpole. I These :areonly ex-cr amples;

Fig. 1 shows preferred-controland switchingcircuits for a 3-phasefour-pole motor, embodying V a double-throw selector-switch! I, adouble-throw starting-switch I8, and seven electromagnetic tions to beindelta, asshowninFigA, and a lower. position for causingsaidconnections to be 1 in Y or-star, as shown inFig. 2. The startingswitch I8 hasan upperv position, for making the:

four-pole connection, either in delta or Y, ac-' cording to the positionof the selector-switch ii, and ithelstarting-switch has also a lowerpositionfor making the two-pol connection-which will be .a four-parallelY-connection, as shown in Fig. 3.

When the starting-switch I8 is in its upper position, its switch-blade2| energizes a circuit 22 whichis connected to a switch-blade 23 of theselector-switch II. When this selector-switch is in its upper position,said switch-blade 23 energizes a delta-connection circuit 24,-whichenergizes the relay or contactor-switchSI. The switch SI thereuponconnects one line-phase, such as A, to the junction-point 0* of theprimary winding of the motor; it also connects the next line-phase, suchas B, to the junction-point a of the primary winding of the motor; andit also connects the third supply-phase, such as .C, to thejunction-point b*.-.

Theselector-switch I I is a two-pole switch,

having a second switch-blade 25twhich, in its upper position,energizes aconductor 25, which energizes the contactor-switch S2, which thereuponconnects the winding-point a to- 0*, b to a andc to b*.

With the starting-switch I 8 still in its upper or four-pole position,but with the selector-switch I! in itslowermost or Y-connectionposition; the

switch-blade 23 energizes a conductor 26',- which energizes acontactor-switch S3 which connects the respective supply-phases A,-B andC to the junction-points a, b and c of the motor-winding. Thesecondswitch-blade 25, in its lower position, energizes a conductor 21, whichenergizes the contactor-switch Se which makes .a star-point connectionbetween the .threejunction-points (1*, 27* and 0* of the motor-winding.

When the starting-switch I8 is moved to its lower position, itsswitch-blade 2| energizes a conductor 28, which energizes the threeremain ing contactor switches S5, S5 and S1. The contactor-switch S5,when energized, connects one of the supply-phases, such-as A, to themotorwinding points I2* and II., respectively; the contactor-switoh stwhen energized, connects the next supply-phase, such as B, to themotorwinding points II? and 9*, respectively;. while thecontactor-swi-tch- S7, I when energized, connects the thirdsupply-phase, such as C, to the motorwinding points 8*. and l,respectively, thus completing the 2-pole supply-line connections. These2-pole supply-phases A, B and. C are not necessarily the same as thei-pole supply-phases A, B and C. Any line-phase may be designated as theprincipal phase A, in either case.

The starting-switch I8 is a three-pole switch, having a secondswitch-blade 29, which, in its lower position, energizes thepreviously-mentioned circuit 27, which energizes the star-connectioncontactor S4 for the junction-points a,

6. b and c*'. The starting-switch I3 has'a thirdz; switch-blade 30,which, in its lower position; en-V ergizes the previously mentionedcircuit 26, which energizes the *contactorSZ for connecting thewinding-points a, b and c to the star-connected junction-points 0*, aand 21*.

Itiwillnbe understood, of course, that itl'may not always be necessaryor desirable to provide a selector-switch for giving the operatoriachoice between a delta-connection and a Y-connection for the four-polemotor-winding connection.

If the delta four-pole connection is to be exclusively used, as shown-inFig. l, the selectorswitch I'I would always be left in its uppermostposition, so that it would eifect a permanent connection between theconductors 22 and 2d; and it would. also permanently energize theconductor EB and the contactcr switch S2, so that there would bepermanent connections between the points a and 0*, b and and crespectively, and this contactor-switch 52 could therefore be omitted.When the selector-switch I? isalways left in its upper position, itcould cbviously be omitted; and the conductor 25 and thecontactor-switch S4 woul not be used at all, and I could also beomitted.

If the Y-type four-pole connection is tc-be exclusively used, as shownin Fig. 2, the selectorswitch ll would always be left in its lowermostposition, which would have the effect of permanently joining theconductors 22 and 26 permanently energizing the-conductor 2? for thestar-point contactor-eswitch St and permanenty cutting outthe conductorI i and the contactorswitch SI, which could, accordingly, be omitted.Since the star-point contactor-switch S4 would thus always be energized(when the four-pole Y-connectionis used to the exclusion of the fourpoledeltaeconnection), then it is obvious that the starepoint connection ofthe three junctionpoints 27* and c could be permanently made, withoutusing saicl-contactor switch SQ.

It will thus be seen that I can from the two-pole, four-parallel,Y-ccnnecticn of Fig. 3, to thefour-pole, two-parallel, Y-oonnection ofFig. 2, by using only five contactorswitches, namely S2, 83,35, S6 andSI, having a total of twelve poles. On the other hand, I can change fromsaid. two-pole, four-parallel, Y-connection of Fig, 3, to the four-pole,two-parallel, deltaconnecticn oriFigle, by using only the fivecontactcr-switches SI, S4, S5, St and S1, having a total of elevenpoles.

In the simplified diagram which is shown in Fig. l, I have notundertaken to show any switchinterlocking means or any switclnsequence13183118. It willlbe obvious that, by opening and closing the variousswitches in the proper sequence, only a relatively small number of theseswitches may be used. for effecting a currentinterruption, the remainingswitches which were inservice being open d after the opening of thecircuit-interrupting switches, thus effecting a saving in the number ofswitches which have to the broadest construction consistent with theirlanguage.

I claim as my invention:

1. A polyphase two-speed, 2-to-1 pole-number, dynamo-electric machinehaving in poles for its high pole-number, where n is an integer;characterized by a primary winding having a plurality of identicalwinding-groups following each other consecutively around thecircumference of the primary winding; permanent group-connectionsforming a separate ring of four winding-groups per phase per four polesof the en pole-number, each ring forming two parallel circuits for said4n pole-number, one of said two parallel circuits of each ringconsisting of two serially connected winding-groups which are similarlysituated in two different north poles at any given'instant, and theother parallel circuit of each ring consisting of two winding-groupswhich are serially connected in the opposite polarity and which aresimilarly situated in two different south poles at the aforesaidinstant; slow-speed polyphase switching-means for energizing each of theaforesaid pairs of parallel circuits from its own proper phase to makethe in-pole connection of the primary winding; and high-speed polyphaseswitching-means for energizing the two intermediate junction-pointsbetween the winding-groups which were in series with each other in theenpole connection, to make a four-parallel connection for each phase forthe Zn-pole connection of the primary winding.

2. A two-speed, three-phase, 2-to-1 polenumber, dynamo-electric machine,characterized by a primary winding having one or more repeatable parts:each repeatable part of the primary winding consisting of twelveconsecutively numerable, identical, winding-groups having the samephase-relations as if said twelve windinggroups followed each otherconsecutively around the circumference of the primary winding; permanentgroup-connections forming three separate rings of winding groups asfollows: I, I, I0, 4, and back to I; 9, 3, 6,12, and back to 9; and 5,ll, 2, 8, and back to 5; slow-speed three-phase switching-means forenergizing the first ring with one phase, entering between i and I andleaving between fl and I, for energizing the second ring with the nextphase, entering between 3 and and leaving between l2 and 9, and forenergizing the third ring with the third phase, entering between H and 2and leaving between 3 and 5; and high-speed star-connection three-phaseswitching-means for entering between 8 and I2, and between 5 and II,with one phase, for entering between [El and 4, and between 9 and 3,with the next phase, for entering between 2 and 8, and between I and i,with the third phase, and for making a common starpoint connection forall of the other terminals of the twelve winding-groups.

3. A two-speed, three-phase, 2-to-1 polenumber, dynamo-electric machine,characterized by a primary winding havin one or more repeat- 8 ableparts: each repeatable part of the primary winding consisting of twelveconsecutively numerable, identical, winding-groups having the samephase-relations as if said twelve windinggroups followed each otherconsecutively around the circumference of the primary winding; permanentgroup-connections forming three separate rings of winding-groups asfollows: I, I, I0, 4, and back to l; 9, 3, 6, l2, and back to 9; and 5,ll, 2, 8, and back to 5; permanent connections between thejunction-points 1-4 and 3-6, between the junction points 9l 2 and l l2,and between the junction-points 58 and 1-40; slow-speed delta-connectionthree-phase switching-means for entering at the connection between thejunction-points 1-10 and 85, with one phase, for entering at theconnection between the junction-points 36 and 4-] with the next phase,and for entering at the connection between the junction-points H-2 and!29, with the third phase; and high-speed star-connection three-phaseswitching-means for entering between 6 and i2, and between 5 and H, withone phase, for entering between it and 4, and between 9 and 3, with thenext phase, for entering between 2 and 8, and between I and 1, with thethird phase, and for making a common starpoint connection for all of theother terminals of the twelve winding-groups.

4. A two-speed, three-phase, 2-to-1 polenumber, dynamo-electric machine,characterized by a primary winding having one or more repeatable parts:each repeatable part of the primary winding consisting of twelveconsecutively numerable, identical, winding-groups having the samephase-relations as if said twelve windinggroups followed each otherconsecutively around the circumference of the primary winding; permanentgroup-connections forming a two-parallel star-connection, of which onephase is serially through first l and then I to the star-point and inthe reverse direction serially through first IE and then ,1 to thestar-point, another phase is serially through first 3 and then 9 to thestarpoint and in the reverse direction serially through first 6 and thenl2 to the star-point, and the third phase is serially through first Hand then 5 to the star-point and in the reverse direction seriallythrough first 2 and then 8 to the star-point; slow-speed three-phaseswitchingmeans for connecting the three-phases of a threephasesupply-line to the respective phaseterminals of the said two-parallelstar-connection; and high-speed, four-parallel star, threephaseswitching-means for entering between 8 and i2, and between 5 and H, withone phase, for entering between i8 and 4, and between 9 and 3, with thenext phase, for entering between 2 and 8, and between i and l, with thethird phase, and for joining the three-phase-terminals of thetwo-parallel star-connection to the starpoint of said two-parallelstar-connection.

LEE A. KILGORE.

No references cited.

